Sherlock:
You and Sherlock have different ideas on how a date should be. He's idea was to go solving crimes, which you do on daily basis anyways, and you idea was a nice dinner with just the two of you. After 5 minutes of staring at you Sherlock gave in and agreed on taking out for dinner. You shared a pizza and talked about everything.
John:
John would often overthink which caused your dates to be a little extreme. Even though you appreciated the act you liked to keep it small and simple. So you took the initiative and ordered china food that you shared while watching a movie.
Moriarty:
Moriarty liked to give you clues to the place you'd have your date. He'd leave small riddles for you to solve and that led you to him, dressed up and flowers in his hand. He'll take you for a nice picnic on the roof where you could look up at the stars.
Greg:
Greg wan't much for going out to eat. Instead he'd cook you a nice meal at his place and then he'll attempt to bake you something for desert but always ends up burning it. So instead you'll share a jar of ice cream.
Mycroft:
Mycroft will be a total gentleman, like always. He'll take you out somewhere new every time and treat you like a queen the entire night. Sometimes you even convince him to let you cook for him, which he likes because then he can take a break from being...well him. He can relax and let you take care of him for once.